Organic white light emitting display apparatus

ABSTRACT

Disclosed is an organic white light emitting display apparatus. The organic white light emitting device includes a first substrate including a first sub-pixel area, a second sub-pixel area, a third sub-pixel area, and an organic light emitting device (OLED) that includes a first electrode, a second electrode, and an organic white light emitting layer interposed between the first and second electrodes, and emits whit light for respective sub-pixel areas, a second substrate including first, second, and third color filters of different colors formed on positions corresponding to the respective sub-pixel areas, the second substrate being arranged to face the first substrate, and a partition wall that is extended to an area between neighboring color filters among the color filters and partitions the sub-pixel areas, the partition wall being formed on the first substrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/222,417 filed Mar. 21, 2014, which claims priority to and the benefitof Korean Patent Application No. 10-2013-0063075, filed on May 31, 2013,in the Korean Intellectual Property Office, the entire contents of bothof which are incorporated herein by reference.

BACKGROUND

Field

The present embodiments relate to an organic white light emittingdisplay apparatus.

Description of the Related Technology

Flat display apparatuses such as a plasma display plane (PDP), liquidcrystal display apparatuses, and organic electroluminescence displayapparatuses are attracting considerable attention.

The liquid crystal display apparatus is not a self-luminous device, buta light-receiving device, and thus there is a limit in brightness,contrast, a vision angle, and forming a large size device. The PDP is aself-luminous device, but the PDP is heavier than other flat displayapparatuses, consumption power is high, and the manufacturing method iscomplicated.

In contrast, the organic electroluminescence display apparatus is aself-luminous device and thus a superior vision angle and contrast areshown, and since a backlight is not necessary, a light and thin type ispossible and less consumption power is used compared to other displayapparatuses. Furthermore, a low DC voltage operation is possible,response speed is high, the temperature range for use is wide, themanufacturing method is simple and inexpensive, and it is resistant toexternal impacts.

In the organic electroluminescence display apparatus, one unit pixel forexpressing natural color is composed of sub-pixels of red R, green G,and blue B, and the sub-pixels may include an organic light emittinglayer that emits white light. When the organic electroluminescencedisplay apparatus is a top emission type, a gap between the organiclight emitting layer that emits light and a color filter is largecompared to a bottom emission type, and thus there is a limit inimplementing desired color.

SUMMARY

The present embodiments provide a top emission type organic white lightemitting display apparatus.

According to an aspect of the present embodiments, there is provided anorganic white light emitting display apparatus including: a firstsubstrate including a first sub-pixel area, a second sub-pixel area, athird sub-pixel area, wherein an organic light emitting device (OLED) isformed in each sub-pixel area, the OLED includes a first electrode, asecond electrode, and an organic white light emitting layer interposedbetween the first and second electrodes and emits white light; a secondsubstrate facing the first substrate and including first, second, andthird color filters of different colors formed on positionscorresponding to the respective sub-pixel areas; and a partition wallformed on the first substrate, extending to an area between neighboringcolor filters among the color filters and partitioning the sub-pixelareas.

The second electrode of the OLED may be formed on the partition wall.

The second substrate may include a black matrix formed between theneighboring color filters.

The partition wall may contain a pigment of a color other than colors ofcolor filters arranged at both sides on the basis of the partition wall.

A partition wall arranged between the first color filter and the secondcolor filter may contain a pigment of the third color, a partition wallarranged between the second color filter and the third color filter maycontain a pigment of the first color, and a partition wall arrangedbetween the third color filter and the first color filter may contain apigment of the second color.

The first color may be red, the second color may be green, and the thirdcolor may be blue.

The organic white light emitting display apparatus of claim 1 mayfurther include: a thin film transistor (TFT) formed on the firstsubstrate; a planarization layer formed on the TFT; a first pixeldefined layer formed on the planarization layer and including aninclined surface and an opening that defines the sub-pixel area; and asecond pixel defined layer formed on the first pixel defined layer,wherein a peripheral part of the first electrode of the OLED is formedon the inclined surface of the first pixel defined layer.

The partition wall may be formed on the second pixel defined layer.

The partition wall and the second pixel defined layer may be integrallyformed.

The second pixel defined layer may cover the first electrode formed onthe inclined surface of the first pixel defined layer.

According to another aspect of the present embodiments, there isprovided an organic white light emitting display apparatus including: afirst substrate including red, green, and blue sub-pixel areas; a secondsubstrate facing the first substrate and including red, green, and bluecolor filters formed at positions corresponding to the sub-pixel areas;a pixel defined layer formed on the first substrate, the pixel definedlayer defines the sub-pixel areas; a partition wall formed on the pixeldefined layer, extending to an area between neighboring color filtersamong the color filters and partitioning the sub-pixel areas; a firstelectrode formed on the first substrate and positioned for each of thesub-pixel areas; an intermediate layer formed on the first electrode andincluding an organic white light emitting layer; and a second electrodeformed on the intermediate layer and the partition wall.

The partition wall may contain a pigment of a color other than colors ofcolor filters arranged at both sides on the basis of the partition wall.

A partition wall extended to an area between the red color filter andthe green color filter may contain a blue pigment, a partition wallextended to an area between the green color filter and the blue colorfilter may contain a red pigment, and a partition wall extended to anarea between the blue color filter and the red color filter may containa green pigment.

The organic white light emitting display apparatus of claim 11 mayfurther include: a thin film transistor (TFT) formed on the firstsubstrate; a planarization layer formed on the TFT; a first pixeldefined layer formed on the planarization layer and including aninclined surface and an opening that defines the sub-pixel area; and asecond pixel defined layer formed on the first pixel defined layer,wherein a peripheral part of the first electrode of an organic lightemitting device is formed on the inclined surface of the first pixeldefined layer.

The first electrode may include reflective metal.

The partition wall may be formed on the second pixel defined layer.

The partition wall and the second pixel defined layer may be integrallyformed.

The second substrate may further include a black matrix formed in anarea between the neighboring color filters.

An upper part of the partition wall may be arranged to correspond to theblack matrix.

The second electrode may have translucency and reflexibility thatreflects at least some of light, which is emitted toward the partitionwall among white light emitted from the intermediate layer, toward thesecond substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the present embodimentswill become more apparent by describing in detail example embodimentsthereof with reference to the attached drawings in which:

FIG. 1 is a cross-sectional diagram schematically illustrating anorganic white light emitting display apparatus according to anembodiment;

FIG. 2 is a cross-sectional diagram illustrating one sub-pixel area ofFIG. 1; and

FIG. 3 is a cross-sectional diagram schematically illustrating anorganic white light emitting display apparatus according to anotherembodiment.

DETAILED DESCRIPTION

As used herein, the term “and/or” includes any and all combinations ofone or more of the associated listed items.

The present embodiments will now be described more fully with referenceto the accompanying drawings, in which example embodiments are shown.The embodiments may, however, be embodied in many different forms andshould not be construed as being limited to the embodiments set forthherein; rather, these embodiments are provided so that this disclosurewill be thorough and complete, and will fully convey the concept of theembodiments to those skilled in the art. In the drawings, thethicknesses of layers and regions are exaggerated for clarity. Termssuch as “including,” “having,” “consist of” may be intended to indicatea plurality of components unless the terms are used with the term“only.”

It will also be understood that when a layer is referred to as being“on” another layer or substrate, it can be directly on the other layeror substrate, or intervening layers may also be present. Like referencenumerals in the drawings denote like elements, and thus theirdescription will be omitted.

FIG. 1 is a cross-sectional diagram schematically illustrating anorganic white light emitting display apparatus (hereinafter, referred toas “display apparatus”) according to an embodiment, and FIG. 2 is across-sectional diagram illustrating one sub-pixel area of FIG. 1.

A first substrate 101 includes a plurality of sub-pixel areas. Forexample, the first substrate 101 may include a first sub-pixel area(red), a second sub-pixel area (green), and a third sub-pixel area(blue), and an organic light emitting device (OLED) that emits whitelight is formed in each sub-pixel area.

A second substrate 210 is arranged to face the first substrate 101, andthe second substrate 201 includes color filters 202R, 202G, and 202Bformed at positions corresponding to respective sub-pixel areas, and ablack matrix formed between the color filters 202R, 202G, and 202B. Thedisplay apparatus according to an embodiment is a top emission type, andwhite light emitted from each sub-pixel area emits red light, greenlight, and blue light as the white light passes through the colorfilters 202R, 202G, and 202B formed on the second substrate 201.

Partition walls 113 a, 113 b, and 113 c, which are extended to areasbetween neighboring color filters 202R, 202G, and 202B and partition thesub-pixel areas, are formed on the first substrate 101. The partitionwalls 113 a, 113 b, and 113 c may be formed to cover one sub-pixel areaentirely or partly.

Color purity at each sub-pixel area may be improved by the partitionwalls 113 a, 113 b, and 113 c. As a comparative example of the presentembodiments, a front-emitting display apparatus without the partitionwalls 113 a, 113 b, and 113 c that partition respective sub-pixel areaswill be described below.

In the display apparatus according to the comparative example of thepresent embodiments, it is assumed that power is supplied only to anOLED formed at a position corresponding to the green color filter 202Gin order to view green light. In this case, there is a gap between thefirst substrate and the second substrate, and thus white light emittedfrom the OLED emits toward all directions. A part of the emitted lightemits toward the red color filter 202R and the blue color filter 202Bincluded in pixels adjacent to the green pixel. Hence, a user views redand blue light as well as green light, and thus it is impossible todisplay pure green light. Color purity of green is deteriorated.

However, according to an embodiment, the partition walls 113 a, 113 b,and 113 c that partition adjacent sub-pixel areas are provided, and thusthe mixture of colors other than the desired colors may be prevented.

Hereinafter, the structure of the display apparatus of the presentembodiments will be described with reference to FIGS. 1 and 2.

The first substrate 101 may be made of glass or plastic. For example,the first substrate 101 may comprise an organic insulation materialselected from a group composed of polyethersulphone (PES), polyacrylate(PAR), polyetherimide (PEI), polyethyelenen napthalate (PEN),polyethyeleneterepthalate (PET), polyphenylene sulphide (PPS),polyallylate, polyimide, polycarbonate (PC), cellulose triacetate (TAC),and cellulose acetate propionate (CAP) which are insulating organicmatters.

The display apparatus according to the present embodiments includes atop emission type display apparatus, and thus the first substrate 101may comprise one or more selected from a group composed of iron, chrome,manganese, nickel, titanium, molybdenum, stainless steel (SUS), Invaralloy, Inconel alloy, and Kovar alloy, but the present embodiments arenot limited thereto.

A buffer layer 102 may be formed on the first substrate 101. The bufferlayer 102 may comprise one of a silicon oxide film, a silicon nitridefilm and multiple films thereof.

A thin film transistor (TFT) is formed on the buffer layer 102. At leastone TFT is formed for each pixel and is electrically connected to theOLED to operate as a driving circuit unit. The TFT broadly includes anactive layer 131, a gate electrode 132, a source electrode 133 s, and adrain electrode 133 d.

The active layer 131 may comprise an inorganic semiconductor such asamorphous silicon or poly silicon, or an organic semiconductor, andincludes a source area 131 s, a drain area 131 d, and a channel area 131c. The source and drain areas 131 s and 131 d may be formed by dopingimpurities to the active layer 131 comprising amorphous silicon or polysilicon. If doped by group III elements such as boron B, a p-typesemiconductor may be formed, and if doped by group V elements such asnitrogen N, an n-type semiconductor may be formed.

A gate insulation layer 103 is formed on the upper part of the activelayer 131, and the gate electrode 132 is formed on a predetermined areaof the upper part of the gate insulation layer 103. The gate insulationlayer 103 is used to insulate the active layer 131 and the gateelectrode 132, and may comprise organic material or inorganic materialsuch as silicon oxide and silicon nitride.

The gate electrode 132 may comprise metal such as Au, Ag, Cu, Ni, Pt,Pd, Al, and Mo, or a metal alloy such as an Al:Nd alloy and a Mo:Walloy, but the present embodiments are not limited thereto, and variousmaterials may be used in consideration of coherence with an adjacentlayer, flatness of a stacked layer, electric resistance, formability,etc.

An interlayer insulation film 104 including a contact hole is formed onthe upper part of the gate electrode 132. The source electrode 133 s andthe drain electrode 133 d are formed to contact the source area and thedrain area of each active layer 131 through the contact hole. The sourceelectrode 133 s and the drain electrode 133 d may comprise metal such asAu, Ag, Cu, Ni, Pt, Pd, Al, and Mo, or a metal alloy such as an Al:Ndalloy and a Mo:W alloy, but the present embodiments are not limitedthereto.

The formed TFT is covered and protected by a planarization layer 105.The planarization layer 105 may comprise an inorganic insulation filmand/or an organic insulation film.

Thereafter, a pixel defined layer 110 made of insulating materials isformed on the planarization layer. The OLED including a first electrode121, an intermediate layer 122, and a second electrode 123 is formed onthe sub-pixel area defined by the pixel-defined layer 110. Here, thefirst electrode, e.g., a peripheral part of the first electrode, mayinclude an inclined surface so that light, which is emitted in ahorizontal direction, e.g., a right and left direction of the displayapparatus of FIG. 2, among white light emitted from the intermediatelayer 122, may be reflected to be emitted toward the second substrate201.

The pixel defined layer may include a first pixel defined layer 111 anda second pixel defined layer 112 formed on the first pixel defined layer111, and the first electrode 121 may be formed between the first pixeldefined layer 111 and the second pixel defined layer 112. The firstpixel defined layer 111 and the second pixel defined layer 112 maycomprise one or more organic materials selected from a group composed ofpolyimide, polyamide, acrylic resin, benzocyclobutene, and phenol resin.

First, an opening is formed so that the peripheral part of the firstpixel defined layer 111 may have an inclined surface, and the firstelectrode 121 is formed on the opening and the inclined surface of thefirst pixel defined layer 111. The first electrode 121 may beelectrically connected to the drain electrode 133 d of the TFT throughthe contact hole formed at the edge of the first pixel defined layer111.

As illustrated in FIG. 2, as the peripheral part of the first electrode121 is formed on the inclined surface of the first pixel defined layer111, the first electrode 121 may also include an inclined surface havinga predetermined angle toward the first substrate 101. The firstelectrode is a reflective electrode, and may contain reflective metalcomprising Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, or an alloy thereof,etc.

Hence, light, which is emitted in a horizontal direction, e.g., towardthe first pixel defined layer 111, among white light emitted from theintermediate layer 122, is reflected to be emitted toward the secondsubstrate 201, and thus optical efficiency may be improved.

The second pixel defined layer 112 including an opening, which hassubstantially the same shape as that of the opening of the first pixeldefined layer, is formed on the first electrode 121, and theintermediate layer 122 including an organic white light emitting layeris formed on the second pixel defined layer 112.

When the organic white light emitting layer of the intermediate layer122 comprises low molecular organic materials, a hole transport layer, ahole injection layer, an electron transport layer, an electron injectionlayer, etc. may be stacked. Furthermore, various other layers may bestacked as necessary. Alternatively, when the organic white lightemitting layer of the intermediate layer 122 comprises high molecularorganic materials, only the hole transport layer may be included on thebasis of the organic white light emitting layer.

The partition walls 113 a, 113 b, and 113 c are formed on the secondpixel defined layer 112, and as described above, the partition walls 113a, 113 b, and 113 c are interposed between areas between the colorfilters 202R, 202G, and 202B, e.g., neighboring sub-pixel areas, so asto spatially separate the pixels and prevent light emitted from eachsub-pixel area from being emitted toward adjacent sub-pixel areas. Thepartition walls 113 a, 113 b, and 113 c may comprise one or organicmaterials selected from a group composed of polyimide, polyamide,acrylic resin, benzocyclobutene, and phenol resin.

A second electrode 123 is formed on the partition walls 113 a, 113 b,and 113 c. The second electrode 123 is a light-transmitting electrodeand may comprise a transparent conductive layer comprising ITO, IZO, ZnOor In2O3, or thin metal such as a Mg:Ag alloy. In particular, When thesecond electrode 123 comprises a thin Mg:Ag alloy, the second electrode123 may have translucency and reflect light, and thus as illustrated inFIG. 2, part of light emitted toward the partition walls 113 a, 113 b,and 113 c among light emitted from the organic white light emittinglayer is reflected in the second electrode 123 to be emitted toward thecolor filters 202R, 202G, and 202B, thereby enhancing light collectingefficiency.

A part of the remaining light that is emitted toward the partition walls113 a, 113 b, and 113 c among light emitted from the organic white lightemitting layer is not reflected by the second electrode 123, and may beabsorbed in the partition walls 113 a, 113 b, and 113 c. Here, in orderto block light that fails to be absorbed in the partition walls 113 a,113 b, and 113 c and is transmitted among light emitted toward thepartition walls 113 a, 113 b, and 113 c, the partition walls 113 a, 113b, and 113 c may include pigments of a color other than the color of thecolor filters 202R, 202G, and 202B arranged at both sides on the basisof the partition walls 113 a, 113 b, and 113 c. For example, thepartition wall 113 b arranged between the red color filter 202R and thegreen color filter 202G may contain blue pigments, the partition wall113 c arranged between the green color filter 202G and the blue colorfilter 202B may contain red pigments, and the partition wall 113 aarranged between the blue color filer 202B and the red color filter 202Rmay contain green pigments.

For example, as illustrated in FIG. 2, light that is emitted toward thepartition wall 113 b among white light emitted from the intermediatelayer 122 corresponding to the red sub-pixel area may be mostly absorbedin the partition wall 113 b, but light that fails to be absorbed in thepartition wall 113 b may pass through the partition wall 113 b andbecome blue light. However, according to an embodiment, the colorfilters 202R and 202G arranged at both sides of the partition wall 113 bdo not transmit blue light, and thus the blue light may not be emittedtoward the external side.

Likewise, since respective partition walls 113 a, 113 b, and 113 ccontain pigments, a little amount of light that fails to be absorbed inthe partition walls 113 a, 113 b, and 113 c may be prevented from beingviewed from the external side, and thus light having a color other thancolors of the sub-pixel areas is prevented from being emitted to anexternal side and color purity at each sub-pixel area may be enhanced.

FIG. 3 is a cross-sectional diagram schematically illustrating anorganic white light emitting display apparatus (hereinafter, referred toas “display apparatus”) according to another embodiment.

The display apparatus according to the present embodiment includes afirst substrate 101 including a plurality of sub-pixel areas, an organiclight emitting device (OLED) formed for each sub-pixel area, and asecond substrate 201 including red, green, and blue color filters 202R,202G, and 202B formed on positions corresponding to respective sub-pixelareas.

Furthermore, partition walls 113 a′, 113 b′, and 113 c′ are extendedtoward areas between neighboring color filters 202R, 202G, and 202B, thesecond electrode 123 is formed on the partition walls 113 a′, 113 b′,and 113 c′, the first electrode 121 is formed on the first pixel definedlayer 111 having an inclined surface so that the peripheral part of thefirst electrode 121 includes an inclined surface, and the partitionwalls 113 a′, 113 b′, and 113 c′ contain pigments as described withreference to FIGS. 1 and 2.

The description will focus on the differences with the description ofFIGS. 1 and 2.

In the display apparatus according to the present embodiment, the secondpixel defined layer and the partition walls 113 a′, 113 b′, and 113 c′may be integrally formed. In this case, the intermediate layer 122 andthe second electrode 123 may be formed on the partition walls 113 a′,113 b′, and 113 c′.

First, an opening is formed so that the peripheral part of the firstpixel defined layer 111 may have an inclined surface, and the firstelectrode 121 is formed on the opening and the inclined surface of thefirst pixel defined layer 111. The peripheral part of the firstelectrode 121 is formed on the inclined surface of the first pixeldefined layer 111, and thus light, which is emitted in a horizontaldirection, e.g., toward the first pixel defined layer 111 among whitelight emitted from the intermediate layer 122, may be reflected in theinclined surface of the first electrode 121 to be emitted toward thesecond substrate 201, as described with reference to FIG. 2.

Next, the partition walls 113 a′, 113 b′, and 113 c′ extended toward theareas between the color filters 202R, 202G, and 202B are formed. Thepartition walls 113 a′, 113 b′, and 113 c′ are interposed between theneighboring sub-pixel areas to spatially separate the pixels and preventlight emitted from each sub-pixel area from being emitted toward theadjacent sub-pixel areas. The partition walls 113 a′, 113 b′, and 113 c′may comprise one or more organic material selected from a group composedof polyimide, polyamide, acrylic resin, benzocyclobutene, and phenolresin. Thereafter, the intermediate layer 122 and the second electrode123 are formed on the partition walls 113 a′, 113 b′, and 113 c′.

Furthermore, some of light emitted from the OLED is reflected to beemitted toward the color filters 202R, 202G, and 202B by the secondelectrode 123 formed on the partition walls 113 a′, 113 b′, and 113 c′,and the partition walls 113 a′, 113 b′, and 113 c′ contain pigments inorder to prevent light that fails to be absorbed in the partition walls113 a′, 113 b′, and 113 c′ and transmits the partition walls 113 a′, 113b′, and 113 c′ from being viewed from the external side, as describedabove.

According to an embodiment, partition walls that entirely or partiallysurround respective sub-pixels are formed, and thus light emitted fromone sub-pixel may be prevented from entering an adjacent sub-pixel,light may be prevented from being emitted through other sub-pixels whenone sub-pixel is turned on, and color purity of light emitted from eachsub-pixel area may be enhanced.

Furthermore, the first electrode is formed to have an inclined surface,and thus light collecting efficiency may be enhanced.

While the present embodiments have been particularly shown and describedwith reference to example embodiments thereof, it will be understood bythose of ordinary skill in the art that various changes in form anddetails may be made therein without departing from the spirit and scopeof the present embodiments as defined by the following claims.

What is claimed is:
 1. A display apparatus comprising: a substrateincluding a first sub-pixel area, a second sub-pixel area, a thirdsub-pixel area; an thin film transistor (TFT) on the substrate; a firstelectrode in each sub-pixel area and electrically connected to the TFT;an organic light emitting layer over the first electrode; a secondelectrode over the organic light emitting layer; and a first pixeldefined layer disposed between the TFT and the first electrode, whereinthe first electrode is disposed over the first pixel defined layer suchthat i) a part of the first electrode and the organic light emittinglayer are disposed within an opening defined in the first pixel definedlayer and ii) a peripheral part of the first electrode is disposed overan inclined surface of the first pixel defined layer surrounding theopening.
 2. The display apparatus of claim 1, wherein the firstelectrode is connected to the TFT via a hole passing through the firstdefined layer.
 3. The display apparatus of claim 1, further comprises asecond pixel defined layer over the first pixel defined layer, whereinat least a portion of the peripheral part of the first electrode isbetween the first pixel defined layer and the second pixel definedlayer.
 4. The display apparatus of claim 1, further comprises aplanarization layer covering the TFT and including a material differentfrom that of the first pixel defined layer.
 5. The display apparatus ofclaim 4, a surface of the planarization layer contacts the part of thefirst electrode corresponding to the opening.
 6. The display apparatusof claim 1, further comprises a resin layer between the peripheral partof the first electrode and the second electrode.
 7. The displayapparatus of claim 1, further comprises: a color filter corresponding toeach sub-pixel area; and a black matrix between a neighboring colorfilters.
 8. The display apparatus of claim 7, further comprises apartition wall, wherein the partition wall includes a pigment.
 9. Thedisplay apparatus of claim 8, wherein the pigment has a color other thancolors of adjacent color filters which are arranged at both sides on thebasis of the partition wall.
 10. The display apparatus of claim 1,wherein the first electrode is reflective and the second electrode hastranslucency.